The Rotproofing of Viscose Rayon II–Treatment of Viscose Rayon with Iron and Chromium Salts

Although Mineral Khaki* treatments are recommended for proofing cotton against micró‐organisms, certain types of chromium and iron pigmentation are shown to be relatively ineffective when applied to viscose rayon, at least when fairly drastic test methods are employed. This is in agreement with results previously obtained with cotton 1,2 . The proof is slightly improved by using potassium chromate as the developing agent, but the sexavalent chromium produced is not fast to leaching. Little improvement is effected by incorporating copper. The viscose rayon takes up considerably less pigment than does cotton under similar conditions, but even where the amounts are almost the same the rayon is still much less resistant to micro‐organisms. This difference may be partly due to the lower inherent resistance of viscose rayon. When chromate development is used the rayon appears to be less damaged (as measured by euprammonium fluidity) than cotton similarly treated.